Balloon catheters are used for a variety of medical procedures, including endovascular treatments. These endovascular treatments are carried out in the lumen of a vascular duct or vessel and have the advantage of being less aggressive and invasive than open surgery. Their conventional use entails the insertion of the balloon catheter into a body conduit at an entrance site and pushing the length of the catheter progressively into the body conduit until the balloon located at the distal end of the balloon catheter reaches the desired site. The balloon is then inflated at that site in order to implement the desired therapy. The body conduit is most often a blood vessel and more particularly an artery, although balloons are used within a variety of other body conduits such as, for example, bile ducts. The inflation of the balloon may be used for various therapeutic reasons. Common uses for balloon catheters include: dilation procedures, occlusion of blood flow, delivery of a pharmaceutical composition to the specific site of inflation, disruption of plaque or thrombus, or to deliver a device to a desired site within the body conduit. Devices most commonly delivered with a catheter balloon include vascular stents and intraluminal vascular grafts both of which may be circumferentially distended by inflation of the balloon until the device is implanted in firm contact with the wall of the blood vessel or conduit.
In use, catheter balloons are known to occasionally rupture due to inflation to higher than designed for pressures. Conventional catheter balloons vent radially in the event of over-pressurization. Sudden rupture and corresponding sudden radial release of inflation pressure fluids or gases has resulted in injury to patients. During a rupture, even if the balloon remains intact, the configuration of the damaged balloon may make withdrawal of the balloon from the body conduit quite difficult. These occasional ruptures can also result in portions of the balloon or emboli being dispersed into the blood vessel or conduit of the patient. Due to displacement of the fragments distally as a result of fluid flow through the blood vessel or conduit, retrieval is difficult and may require interventional surgery. It is further difficult to ascertain with certainty that all pieces have been retrieved. A sudden rupture and release of inflation media due to over-pressurization may also result in damage to the vessel wall requiring additional surgery.
U.S. Pat. No. 5,221,258 to Shturman teaches a catheter balloon having a longitudinal segment of weakness intended to allow the intentional rupture of the balloon between its ends in order to release a device contained within the balloon. Shturman also describes that the balloon may be provided with a portion of larger diameter than the remainder of the balloon in order that the higher hoop stress in the larger diameter portion results in rupture.
U.S. Pat. No. 6,375,637 to Campbell shows a controlled failure balloon mechanism with provision of at least one aperture or slit at least partially through the thickness of the balloon material in at least one end region of the balloon where it is secured to the exterior of the catheter shaft.
None of the prior art balloon catheters provide catheter balloon seals having reliable and controlled failure mechanisms for the prevention of catastrophic failure of the balloon material during overpressure conditions. The present invention provides a balloon catheter with a safe failure design preventing fragmentation of the balloon material in the event of a rupture and further, allowing for safe and easy retrieval of the balloon material from a patient.